Mercedes-Benz claims its new CLA180 BlueEfficiency Edition is the world’s most aerodynamically efficient series production road car, with an overall drag co-efficient of 0.22.

The saloon forms part of a five strong line-up of CLA models set to make their public debut at next month’s Geneva motor show. In comparison to the CLA’s cD figure, Toyota’s Prius is rated at 0.25 and the BMW 320d EfficientDynamics at 0.26.

The key to the car’s wind cheating properties is a relatively small frontal area (2.21m2) and a series of small but effective refinements not found on other CLA models. These include a reworked front apron, improved sealing for the headlamps surrounds, an adjustable radiator shutter and serrated spoilers to guide air into the wheelhouses.

Powered by a 1.6-litre four-cylinder petrol engine developed with Renault, the CLA has 120bhp and. It reaches 100kph in 9.9sec.

Mercedes-Benz is planning to extend its aerodynamic development work with the opening of a new wind tunnel at its Sindelfingen R&D facility. It includes a rolling road as part of a 19m long floor area and is capable of providing measurements at speeds up to 266kph Until now, Mercedes-Benz has relied heavily on the University of Stuttgart's wind tunnel, which celebrated its 70th anniversary earlier this week.